JP4023979B2 - Optical digitizer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical digitizer, and more particularly to an optical digitizer that can be applied to a PDA such as an electronic notebook, a cellular phone, and the like and can be manufactured at a low cost.
[0002]
[Prior art]
Recently, portable pen input computers such as PDAs are becoming popular. Many of these are equipped with a pressure-sensitive resistive film type touch panel on the liquid crystal display device, so that you can operate the menu screen and input graphics by touching or drawing with your finger or pen, Users can use it like a normal pen and notebook. However, in the pressure sensitive resistance type touch panel, since the pressure sensitive resistance film is placed on the liquid crystal display device, the display of the liquid crystal display device may become dark due to its structure. In particular, in recent years, a reflection type liquid crystal display device has attracted attention. However, in the reflection type liquid crystal method, the effect of reducing the amount of light when a pressure-sensitive resistance film is used appears significantly. This is because in the backlight type liquid crystal display device, the light from the backlight passes only once through the pressure-sensitive resistance film. However, in the case of the reflective type, the external light first passes through the pressure-sensitive resistance film and is reflected back. This is because the amount of light attenuation simply doubles that of the backlight type because the incident light again passes through the pressure-sensitive resistance film. Therefore, it has been proposed to mount an optical digitizer in place of the pressure-sensitive resistive film type touch panel.
[0003]
FIG. 5 shows an example of a conventionally proposed optical digitizer. FIG. 5A is a schematic plan view of the optical digitizer, and FIG. 5B is a side view of a partial cross section thereof. As shown in the figure, when a finger 2 as an indicator is placed on the detection surface 1, the indicated position coordinates are detected by the principle of triangulation by two detection units 3 provided above the detection surface 1. is there. As shown in FIG. 5B, the detection unit 3 includes a half mirror or a tunnel mirror 14 in front of the imaging lens 9 of the linear image sensor 13 so that the optical axis of the LED light source 31 is the same as that of the linear image sensor 13. Each is arranged so as to coincide with the optical axis. When a light beam emitted from the LED light source 31 strikes the retroreflective member 22 provided around the detection surface 1, the retroreflective characteristic causes the light incident thereon to be reflected so as to return straight in the incident direction. When the finger 2 is placed on the detection surface 1, the light at that portion is blocked, so that the linear image sensor 13 can detect it as a shadow. The direction of the shadow of the reflected light from the LED is imaged by the linear image sensor 13 and converted into an electrical signal by the left and right detection units 3 and 3, and these signals are calculated using the principle of triangulation. By performing the processing, the designated position coordinates of the finger 2 can be detected. The conventional example shown in the figure is a display device integrated optical digitizer in which the display device 20 is stacked on the detection surface.
[0004]
There is also a type of optical digitizer in which a light beam such as a laser beam is swung by a rotating mirror as a light source, and retroreflected light from a position indicator is detected by a sensor or the like through a reverse path.
[0005]
In such a conventional optical digitizer, the detection unit 3 is fixed to a portion different from the transparent input flat plate forming the detection surface 1 by using an adjustment screw 16. The viewing angle has been adjusted to achieve a viewing angle that is close to the detection surface.
[0006]
[Problems to be solved by the invention]
However, the conventional optical digitizer requires a half mirror, its holder, etc., and is expensive, so there is an economical problem. Furthermore, since the detection unit becomes large and cannot be thinned due to the influence of parts such as the half mirror and the light source portion, it is difficult to apply the optical digitizer to a small electronic device such as a PDA. Furthermore, since the conventional optical digitizer uses a half mirror or the like, there is a case in which a reduction in the amount of light at that portion also becomes a problem.
[0007]
Further, the method using a laser beam requires a rotating mirror for rotating the light beam, and also requires expensive parts such as a laser element, a laser driving circuit, and a collimator lens system, and the configuration is complicated and expensive as a whole. It became a device and was not suitable for miniaturization.
[0008]
In addition, since conventional optical digitizers require a viewing angle adjustment mechanism, this part also hinders miniaturization, and there are also problems of high material costs and adjustment costs, so mass production is inexpensive. It was not suitable for.
[0009]
In view of such circumstances, the present invention can be reduced in size because the detection unit can be made thin and does not protrude, and a viewing angle adjustment mechanism or the like is unnecessary. It is intended to provide an optical digitizer that can be applied to electronic devices.
[0010]
[Means for Solving the Problems]
In order to achieve the above-described object of the present invention, an optical digitizer for detecting a pointing position coordinate of a pointer on a detection surface according to the present invention includes a light source for emitting a light beam and at least three sides around the detection surface. A retroreflective member that retroreflects a light beam emitted from the light source, and a light beam emitted from the light source and retroreflected from the retroreflective member. An imaging means for imaging the indicator and converting it into an electrical signal, and a shape having a plane above and below it sliced parallel to the optical axis in order to reduce the thickness in the direction perpendicular to the detection surface An image forming lens for forming an image on the imaging means, and in order to bring the optical axis of the light beam emitted from the light source close to the optical axis of the image forming lens, the light source is placed on the image forming lens. It is provided in contact with each other.
[0011]
The light source is cut off if it is provided close to the upper plane of the imaging lens or if the imaging lens is a fan shape that is V-shaped so that the incident side of the light is narrow and the imaging means side is wide. You may arrange | position at least 2 light source so that it may adjoin to a side plane.
[0012]
The imaging lens is provided with a stop on the front surface on the light incident side. Further, the imaging lens may be installed on the input flat plate that forms the detection surface, or may be integrally formed with the input flat plate that forms the detection surface.
[0013]
A mirror means for refracting light from the imaging lens by 90 degrees to form an image on the imaging means may be further provided between the imaging lens and the imaging means.
[0014]
A display device having a display surface stacked on the detection surface may be further provided as an optical digitizer with a display device.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described together with illustrated examples. In addition, the component shown with the same referential mark used by description of a prior art shows the same component. FIG. 1 is a view showing a first embodiment of the optical digitizer of the present invention, FIG. 1 (a) is a schematic plan view thereof, and FIG. 1 (b) is a side view thereof.
[0016]
As shown in the figure, the detection unit 3 of the optical digitizer of the present invention includes an LED 31 as a light source, a linear image sensor 13 as an imaging means, an imaging lens 4 for imaging light onto the image sensor, and an incident light beam. And an aperture 6 for limiting the amount of The most characteristic feature of this embodiment is the shape of the imaging lens 4. As illustrated, the imaging lens 4 has a shape that is sliced parallel to the optical axis of a lens such as a plano-convex lens. Here, the imaging lens preferably has an aspherical convex surface in order to prevent defocusing at the end of the image sensor. And in order to make the optical axis of the light ray which LED emits, and the optical axis of an imaging lens approach, LED31 is provided in the part of the upper plane among the cut surfaces. In order to detect the direction of shadow using retroreflected light, it is ideal to place a point light source close to the part of the imaging lens where the light beam is focused, but in a general wide-angle lens, a concave lens is placed before the diaphragm. Therefore, it becomes difficult to provide the diaphragm and the light source close to each other. However, in the present invention, the diaphragm 6 can be provided in front of the imaging lens 4 as shown in the figure, so that the entrance pupil of the diaphragm 6 and the light emitting point of the LED 31 can be brought close to each other.
[0017]
Moreover, you may further provide the display apparatus 20 with the display surface stacked under the detection surface 1 as needed. By doing so, a so-called touch panel display device can be realized. According to the present invention, since there is no factor for attenuating light, it is possible to maintain good brightness even if the display device 20 is a reflective liquid crystal.
[0018]
The detection units 3 configured as described above are arranged at two locations on the same plane as the transparent input flat plate 10 that forms the detection surface 1. With the optical digitizer configured as described above, the designated position coordinates of the indicator 2 such as a pen or a finger designated on the detection surface 1 are detected. That is, a part of the light from the LED 31 is blocked by the finger 2 that is an object placed on the detection surface 1, and the direction of the blocked light, that is, the direction of the shadow is detected by the linear image sensor 13. By performing this with the two detection units 3 at known positions, the position coordinates of the finger 2 can be accurately calculated by the principle of triangulation. More specifically, the light emitted from the LED 31 passes through the detection surface 1 and enters the retroreflective member 22 that surrounds the three sides around the detection surface, and retroreflects to return to the original direction. Then, the returned light enters the imaging lens 4 through the diaphragm 6 and forms an image on the linear image sensor 13. When the finger 2 blocks light from the light source 31 in this state, the linear image sensor 13 becomes a shadow, and the shadowed direction can be detected. By detecting the direction of the shadow by the left and right detection units 3 and 3, respectively, the designated position coordinates of the finger 2 are detected using the principle of triangulation.
[0019]
In the illustrated example, the retroreflective member 22 is provided so as to surround the three sides around the detection surface. Instead of this, a dedicated pen having the retroreflective member 22 wound around the tip is used as an indicator instead. Of course it is also possible. In this case, the linear image sensor 13 does not detect anything because the light emitted from the LED 31 does not return when the dedicated pen is not placed, but when the dedicated pen is placed on the detection surface, Since the retroreflected light from the retroreflective member 22 can be detected, it is possible to detect the designated position coordinates of the dedicated pen from the direction of the retroreflected light using the principle of triangulation.
[0020]
As described above, according to the first embodiment of the optical digitizer of the present invention, the imaging lens is a so-called slice lens, and the LED 31 is provided thereon, so that the optical axis of the light beam emitted from the LED 31 and the light of the imaging lens 4 can be obtained. Since the shaft can be brought closer, parts such as a half mirror, which has been conventionally required, are not required. Accordingly, the number of parts is reduced, the cost is reduced, and the half mirror that causes a decrease in the amount of light can be eliminated, so that the detection sensitivity is increased. The detection unit itself can be made thin by thinning the imaging lens. In addition, since it is only necessary to fix the sliced imaging lens on the input plane plate, it is not necessary to adjust the viewing angle in the vertical direction. The unit can be downsized.
[0021]
Next, a second embodiment of the optical digitizer of the present invention will be described with reference to FIG. FIG. 2 (a) is a schematic plan view of a detection unit in the second embodiment of the optical digitizer of the present invention, and FIG. 2 (b) is a side view thereof. Other parts, such as the detection surface, are the same as in the first embodiment, and are not shown. The most characteristic feature of this embodiment is that the slice lens shown in the first embodiment is further shaped like a fan in a V shape. As shown in FIG. 2A, the imaging lens 5 of the present embodiment has a V-shaped shape so that the light incident side from the detection surface 1 is narrow and the linear image sensor 13 side is wide. . Then, two LEDs 32 and 33 are arranged on the cut side plane. By doing so, the detection unit can be made thinner than the first embodiment by the thickness of the LED. Since the imaging lens has a V-shaped shape, the light emitting point of the LED can be brought close to the entrance pupil (aperture 6) of the imaging lens, and the direction of the shadow is detected using retroreflected light. The structure is close to the ideal above. FIG. 2 shows a case where two LEDs are used, but it is of course possible to use only one LED. However, if two LEDs 32 and 33 are used, a sufficient amount of light can be obtained. Even if the emission angle of the LED of this LED is narrow, since the two are combined, a sufficient emission angle can be obtained. Also, if the light incident side from the detection surface 1 is made sufficiently narrow and the LEDs 32 and 33 are provided close to both sides, they will have the same effect as the diaphragm, so the diaphragm 6 itself is also unnecessary. It becomes.
[0022]
The method for detecting the designated position coordinates of the indicator designated on the detection surface using the detection unit configured as described above is the same as that in the first embodiment, and the description thereof will be omitted.
[0023]
Thus, according to the second embodiment of the optical digitizer of the present invention, the imaging lens is a so-called slice lens, and the light incident side to the imaging lens is narrow and the image sensor side is wide. It is possible to make the optical axis of the light beam emitted from the LED closer to the optical axis of the imaging lens by arranging the LEDs on both sides so as to be close to the side plane, and to make two LEDs. Since it is used, a sufficient amount of light can be obtained even with an inexpensive LED. Moreover, it can be made thinner by the thickness of the LED than the detection unit of the first embodiment.
[0024]
FIG. 3 shows a third embodiment of the optical digitizer of the present invention. In the above-described embodiment, the imaging lens that has been cut in advance is provided on the transparent input plane plate that forms the detection surface. However, in the third embodiment shown in FIG. It is integrally molded with the input flat plate to be formed. That is, as can be seen from the side view of the optical digitizer of the third embodiment shown in FIG. 3, the input flat plate is made of an integrally molded acrylic member 11 made of acrylic resin, and a convex portion 40 is formed at a predetermined portion thereof. It is formed so that it functions as an imaging lens part. Thus, by integrally molding the input flat plate 11 and the imaging lens unit 40, it is possible to reduce the number of parts and manufacturing processes, and it is possible to manufacture a cheaper optical digitizer. Furthermore, with such a structure, a viewing angle adjustment mechanism is not required, and an optical digitizer that does not require adjustment can be realized.
[0025]
In the embodiments described so far, the linear image sensor 13 has been described as having a low (narrow) height (width) compared to the imaging lens. However, the present invention is not limited to this, for example, When the image sensor is larger than the imaging lens, a mirror unit 18 may be provided and the linear image sensor 13 may be provided on the back side of the input flat plate 11 as shown in FIG. With such a configuration, the light from the imaging lens unit 40 can be refracted by 90 degrees to form an image on the linear image sensor 13. Therefore, even if the linear image sensor is large, the detection unit can be made small. Become. In this case, the convex portion of the mirror portion 18 is also integrally formed with the input flat plate 11, whereby the number of parts and the manufacturing process can be reduced, and a detection unit that does not require adjustment can be manufactured. FIG. 4 shows an example of the optical digitizer when the pen 22 provided with the retroreflective member 22 at the tip is used as the indicator. However, as in the other embodiments, even if it is a finger blocking method, Of course.
[0026]
Note that the optical digitizer of the present invention is not limited to the above-described illustrated examples, and various modifications can be made without departing from the scope of the present invention. For example, the optical digitizer of the present invention may be a blocking type, a type that uses retroreflection from a pen, or a combination thereof. The linear image sensor can use various image pickup means such as a CCD and a CMOS. Furthermore, although acrylic resin has been exemplified as the material of the input flat plate, various materials such as polycarbonate can be used. Further, as retroreflective members, there are those using glass beads, etc., but various materials such as those in which small corner cube prisms are spread or white members having high reflectivity can be used.
[0027]
【The invention's effect】
As described above, according to the optical digitizer of the present invention, the detection unit can be thinned by slicing the lens thinly and arranging the light source on the upper surface or side surface thereof, so that the viewing angle can be adjusted without protruding. Since a mechanism or the like is not required, it is possible to reduce the size and to achieve an excellent effect that mass production can be performed at a lower cost. Therefore, the optical digitizer of the present invention can be applied to the liquid crystal surface of a small electronic device such as a PDA without harming its shape.
[Brief description of the drawings]
FIG. 1 is a view showing a first embodiment of an optical digitizer of the present invention, in which (a) is a schematic plan view thereof, and (b) is a side view thereof.
FIG. 2 is a view showing a second embodiment of the optical digitizer of the present invention, in which (a) is a schematic plan view of the detection unit, and (b) is a side view of the detection unit. .
FIG. 3 is a diagram showing a third embodiment of the optical digitizer of the present invention.
FIG. 4 is a diagram showing a case where a mirror portion is further provided on the input plane plate of the optical digitizer of the present invention.
5A and 5B are diagrams showing a conventional optical digitizer, in which FIG. 5A is a schematic plan view thereof, and FIG. 5B is a side view thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Detection surface 2 Indicator 3 Detection unit 4,5,9 Imaging lens 10,11 Input plane board 13 Linear image sensor 14 Tunnel mirror 16 Adjustment screw 18 Mirror part 20 Display apparatus 22 Retroreflective member 31 Light source 40 Imaging lens part

Claims (8)

An optical digitizer for detecting the pointing position coordinates of the pointer on the detection surface, the optical digitizer,
A light source for emitting light;
A retroreflective member that retroreflects light rays emitted from the light source, provided so as to surround at least three sides around the detection surface, or provided on the indicator;
Imaging means comprising an image sensor for imaging the indicator and converting it into an electrical signal using a light beam emitted from the light source and retroreflected from the retroreflective member;
To reduce the thickness of the vertical direction with respect to the detection surface, a part of the axisymmetric curved surface of the lens consisting of axisymmetric curved surface with a shape having a plane above and below sliced parallel to the optical axis An imaging lens for forming an image on the imaging means, which has a fan shape that is V-shaped so that the light incident side is narrow and the imaging means side is wide ;
The light source is provided close to the cut side plane of the imaging lens in order to bring the optical axis of the light beam emitted from the light source close to the optical axis of the imaging lens. Optical digitizer. 2. The optical digitizer according to claim 1, wherein at least two light sources are provided close to the cut side plane of the imaging lens. 3. The optical digitizer according to claim 1 , wherein the imaging lens is provided with a stop on a front surface on an incident side of the imaging lens. 4. An optical digitizer as claimed in any one of claims 1 to 3, wherein the imaging lens, an optical digitizer, characterized in that installed in the input plane board that forms the detection surface. An optical digitizer as claimed in any one of claims 1 to 4, wherein the imaging lens, an optical digitizer, characterized in that it is molded integrally with the input plane plate forming said detection surface. An optical digitizer as claimed in any one of claims 1 to 5 imaged during the imaging means and the imaging lens, the imaging means and is refracted 90 degrees light from the imaging lens An optical digitizer characterized in that it further comprises mirror means. The optical digitizer according to any one of claims 1 to 6 , further comprising a display device having a display surface stacked on the detection surface. 8. The optical digitizer according to claim 7 , wherein the display device is a reflective liquid crystal display device.

Images